Abstract: At present,lapel ease allowance is designed mainly on the basis of experience.There exist shortcomings in one way or another in the commonly used methods for calculating lapel ease allowance.When particular proportion of the top collar to collar stand adopted,it tends to occur errors if the existing computation methods is used for it.With a view to solving this problem,the paper has introduced a new method: first to calculate the average radius of the two circles of collar stand and outer length of the lapel,then,obtain the difference of the circles through the difference of the radii.According to the figure of human body,the changeable ease allowance of the lapel is figured out through reasonable proportioning and computation.Through testing and comparison,it has proved that this method can solve the problem stated above and it is more scientific,accurate and practical.